Audio Video Bridging (AVB) is a networking protocol pertaining to streaming audio and/or video data via a network (e.g., an Ethernet network), described in IEEE 802.1 standards. An AVB network may include one or more talkers (e.g., transmitter nodes) and one or more listeners (e.g., receiver nodes) for transmitting and receiving audio/video data according to the Audio/video transport protocol (AVTP), described in the IEEE 1722 standard.
Similarly, Time-Sensitive Networking (TSN) is a set of IEEE 802 Ethernet sub-standards. These standards enable deterministic real-time communication over Ethernet. Time-Sensitive Networking ensures a bounded maximum latency for scheduled traffic through switched networks. Possible applications include converged networks with real time Audio/Video Streaming and real-time control streams which are used in automotive or industrial control facilities.
When audio/video data is transmitted from a talker to a listener, the data may pass through hops (e.g., bridges or switches) located in the network. For example, the network may comprise bridges that receive the data, determine a next location (e.g., a next bridge), and send the data to the next location toward the listener. The time the data takes to be transmitted from the talker to the listener, including the time taken for the bridge(s) to perform these actions, constitutes a latency.
One of the features of AVB and TSN networks is the definition of Quality of Service (QoS) requirements and associated traffic or Stream Reservation (SR) classes. Each traffic class defines a maximum latency based on the presence of a maximum number of seven hops between the talker and the listener in the network. The latency includes the accumulated time it takes for the data to transit through the switches (accumulated transit time). The maximum latency may include the accumulated transit time plus a predetermined margin.
For example, AVB traffic class A is the highest class and defines a maximum latency of 2 ms over seven hops. Traffic class A is particularly suited for the transmission of low latency audio data. Traffic class B defines a maximum latency of 50 ms over seven hops and can be used for the transmission of video data. Additional, lower traffic classes include so-called traffic class 64Sample 48 kHz (Class 64×48 k) and traffic class 64Sample 44.1 kHz (Class 64×44.1 k). These classes can define even lower maximum latencies.
Examples of traffic classes in the context of AVB are described in Automotive Ethernet AVB Functional and Interoperability Specification Revision 1.4.
Generally, relative to the other classes, the transmission of data of a higher traffic class (e.g. AVB traffic class A) causes a relatively higher processing (e.g., interrupt) load on the listener node. However, in some networks, not all listener nodes have the performance required to process such high class traffic.
The present invention aims to address this problem.